Chao Wang updated PIG-1104:
Status: Patch Available (was: Open)
> [zebra] Provide streaming support in Zebra.
> Key: PIG-1104
> URL: https://issues.apache.org/jira/browse/PIG-1104
> Project: Pig
> Issue Type: New Feature
> Affects Versions: 0.4.0
> Reporter: Chao Wang
> Assignee: Chao Wang
> Fix For: 0.6.0, 0.7.0
> Attachments: PIG-1104.patch
> Hadoop streaming is very popular among Hadoop users. The main attraction is
> the simplicity of use. A user can write the application logic in any language
> and process large amounts of data using Hadoop framework. As more people
> start to use Zebra to store their data, we expect users would like to run
> Hadoop streaming scripts to easily process Zebra tables.
> The following lists a simple example of using Hadoop streaming to access
> Zebra data. It loads data from foo table using Zebra's TableInputFormat and
> then writes the data into output using default TextOutputFormat.
> $ hadoop jar hadoop-streaming.jar -D mapred.reduce.tasks=0 -input foo -output
> output -mapper 'cat' -inputformat
> More detailed, Zebra uses Pig DefaultTuple implementation of Tuple for its
> records. Currently, when Zebra's TableInputFormat is used for input, the user
> script sees each line containing " key_if_any\tTuple.toString() ". We plan to
> generate CSV format representation of our Pig tuples. To this end, we plan to
> do the following:
> 1) Derive a sub class ZupleTuple from pig's DefaultTuple class and override
> its toString() method to present the data into CSV format.
> 2) On Zebra side, the tuple factory should be changed to create ZebraTuple
> objects, instead of DefaultTuple objects.
> Note that we can only support streaming on the input side - ability to use
> streaming to read data from Zebra tables. For the output side, the streaming
> support is not feasible, since the streaming mapper or reducer only emits
> "Text\tText", the output collector has no way of knowing how to convert this
> to (BytesWritable,Tuple).
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